Arrangement in heating furnaces or heat treatment furnaces of the walking beam type for rotating the objects to be heated therein, so as to obtain uniform heating of said objects

ABSTRACT

An arrangement in heating furnaces or heat treatment furnaces of the walking beam type for rotating the objects to be heated therein so as to obtain uniform heating of said objects. The hearth of the furnace includes at least one movable walking beam, the stationary portion of the hearth presents one or more support surfaces which are terminated by a relatively steep, downwardly sloping portion. The walking beam presents upright members for engaging behind the billets and rolling said billets by pushing them over the lip of the steep, downwardly sloping portion.

O United States Patent 11113,599,944

[72] Inventor John Erland Erixson {56] References Cited stem, Sweden UNITED STATES PATENTS 5; 2Y 2 1969 1,965,868 7/1934 Vickers .1 263/6 A x e d 2,620,174 12/1952 Passafaro 198/219 ux k all k U M 2,796,780 6/1957 MacGregoretal... 198/219 x l 1 g l gs 2,858,122 10/1958 MacGregor 263/6 A Priority p 1968 3,128,651 4/1964 Peterson 198/219 [33] Sweden Primary Examiner-Charels J. Myhre [31] 11,781/68 Attorney-Stevens, Davis, Miller & Mosher [54] ARRANGEMENT IN HEATING FURNACES OR THE ABSTRACT: An arrangement in heating furnaces or heat g q BE HEATED THERE so As To treatment furnaces of the walking beam type for rotating the 8 IN UN?FORM HEATING OF SAID 0B ECTS objects to be heated therein so as to obtain uniform heating of CI n D J said objects. The hearth of the furnace includes at least one 5 rawmg movable walking beam, the stationary portion of the hearth [52] U.S.Cl 263/6 A presents one or more support surfaces which are terminated [51 Int. Cl ..B65g 25/04, by a relatively steep, downwardly sloping portion. The walking F27b 9/14 beam presents upright members for engaging behind the bil- [50] Field of Search 263/6, 6 A; lets and rolling said billets by pushing them over the lip of the 198/219 steep, downwardly sloping portion.

7/ /4- f0 f9 /4 29 /5 7 3 I m 77, /s /4 /5 A? LL 1\ \1 1 k \1\\/ x 1\ 2 'll 1 1 1 7 ,7 22/ 77 /6 24 f6 24 f6 26 27 20 26 23 20 f6 2/ /8 2/ 26 22 Z5 PATENTEI] AUG] 7 |97l SHEET 2 OF 4 for rotating the objects, such as billets, to be heated therein, so

as to obtain uniform heating of said billets. The hearth of the furnace includes at least one movable walking beam and the stationary portion of the hearth presents one or more support surfaces terminated by a relatively steeply downwardly sloping portion.

When heating billets or like objects in furnaces which are only heated from above, the temperature of the blanks are not heated to a uniform temperature throughout, partly as a result of the one-sided supply of heat and partly as a result of the cooling effect of the hearth. The difference in temperature occurring between the upper and lower side of the billet has a harmful effect on subsequent rolling operations, in that the bullet tends to bend.

This difference in temperature increases with the heating rate, but can be equalized to a certain extent if the billet, subsequent to being heated to the intended temperature, is allowed to remain for a certain length of time in the furnace before being discharged therefrom. In the best of cases the difference in temperature is equalized by an amount which substantially corresponds to the amount of heat lost to the furnace hearth.

When heating certain grades of steel, e.g. steels which are sensitive to decarborization, it is of great importance to the magnitude of decarborization that heating is effected rapidly.

Since, however, this can result in temperature differences of such magnitude that trouble-free rolling is made impossible, it is necessary to attempt to reach a compromise between the desire for slight decarborization and a trouble'free rolling, since a long stay time in the furnace results in increased decarborization, it is impossible to permit the billet to remain in the furnace for long periods of time for the purpose of equalizing the temperature thereof.

In order to prevent decarborization increasing over the level which need arise when heating to the fastest extent possible, the method can be adopted wherein the billets are turned. Since, when applying this method, different sides of the billet are heated, and since the side of the billet previously colled by the hearth is turned and heated, the aforementioned temperature difference can be practically completely equalized, while at the same time the heating time is shortened.

In pusher furnaces, where the billets lie in close contiguous relationship, it is not possible to turn the billets until the heating operation is completed, since it is only then that the leading billets in a row can be separated from each other. Consequently, the billets are generally turned manually. On the other hand, in walking beam furnaces in which the blanks are conveyed through the furnace in spaced relationship during the whole of the heating period it is possible to rotate the blanks at any position along the system.

Manual turning of the blanks, however, is strenuous and difficult to effect, and therefore is not a fully acceptable method.

In order to avoid the manual method of turning the billets or blanks and in an attempt to find an automatically operating turning sequence, an arrangement has been suggested by means of which the billets can be turned through 90 at each feeding movement of the conveyor. This arrangement mainly comprises a stationary hearth having a sawtoothlike appearance when viewed from the side in which the billets are advanced by means of special pushing devices arranged at each sawtoothlike portion of the hearth. These pushing devices substantially comprise rods which extend through the hearth of the furnace and project into the furnace room, while being guided parallel with the conveying surfaces of the sawtoothlike portions and operated by means of machinery situated beneath the hearth ofthe furnace. The pushing devices are adapted to push the billets forwards, towards and over the crown of the teeth, thereby rolling or tipping the billets and causing them to turn through The billets, however, fall down onto preceding pushing devices, which are then subjected to considerable strain and wear. This arrangement is also accompanied by the disadvantage wherein the pushing devices, for the purpose of guiding the same, must be passed through bearings situated in the hearth, which bearings are subjected to wear and the influence of red-hot scale, etc. In practice, the arrangement is found particularly expensive from the point of view of maintenance, owing to the wear of said movable parts.

One object of the invention is to eliminate these disad vantages, and the invention is mainly characterized in that the walking beam presents upright members adapted to engage behind the billets and roll or tip the same by pushing them over the edge of the dip formed between adjacent support surfaces.

In a preferred embodiment, the furnace has a, stationary hearth, exhibiting a sawtoothlike appearance when viewed from the side, and one or more movable walking beams cooperating with the hearth. These beams may have the same sawtooth profile as the stationary hearth, or, alternatively, may be devoid of teeth and planar and provided instead with carrier members or dogs in the form of upright members, arranged in a spaced relationship which coincides with the spacing of the sawtoothlike configurations.

The beams operate with lifting and lowering movements and with reciprocating movements, the directions of which movements are substantially parallel with the. billet support surfaces or conveying surfaces directed obliquely forwardly and upwardly towards the crowns or lips of the sawtoothlike portions.

When the movable beams have the same side profile as the stationary hearth, the billets, upon movement of the beams, will be projected forwards and upwards on the support surfaces of the stationary hearth towards the lips by means of the front, steep surfaces depending from the lips located'on the movable beams. The billets, however, while being turned then fall down onto the movable beams.

In order to avoid this, the movable beams, as indicated above, can be made substantially planar and provided with upright dogs, which are of such a height that they are capable of pushing the billets forwards on the support or conveying surfaces, while the upper surfaces of the beams are still located beneath the surfaces of the stationary hearth. Subsequent to being turned, the billets will then fall down onto the stationary hearth.

The forward and upward movement of the movable beams parallel with the plane of the inclined support surfaces is obtained by arranging sloping surfaces on the underside of the beams through the intermediary of which surfaces the beams are supported on wheels, the underside of said surfaces extending parallel with the surface of the sloping support surfaces on the stationary hearth; as a result of this arrangement, the beams are imparted a rhombic movement cycle.

The invention will now be described in more detail with reference to a number of embodiments shown diagrammatically in the accompanying drawings, further characterizing features of the invention being disclosed in conjunction therewith.

FIG. 1 illustrates diagrammatically a longitudinal section through one embodiment of the invention in a walking-beamtype heating furnace, showing the billets being moved stepwise through the hot atmosphere of the furnace on a billet turning means characteristic of the invention,

FIG. 2 is a cross-sectional part view of the furnace illustrated in FIG. 1.

FIG. 3 is a side view showing diagrammatically the relative positions between the stationary hearth and the movable beams shown in FIG. 1, in one stage of the cyclic movement of said beams, that is during the return movement of said beams,

FIG. 4 shows the mutual positions of the same elements subsequent to the beam being raised and having lifted the majority of billets with the exception of each leading billet situated on each support surface of the hearth adjacent the crown or lip,

FIG 5 shows the mutual positions of the same elements, subsequent to the walking beams completing their horizontal forward movement, and the billets remaining on the hearth. as shown in FIG. 4, being tipped over the crowns of the support surfaces as a result of the pushing action of the steep surfaces on the moving beams.

FIG. 6 shows the mutual positions of the same elements. subsequent to completion of the vertical lowering movements of the beams,

FIG. 7 shows substantially the same furnace as that illustrated in FIG. 1, wherein. however. the rectangular movement pattern of the walking beams is modified by special means to a rhomboidlike movement,

FIG. 8 shows diagrammatically a longitudinal section of another embodiment of the invention, wherein the movement of the walking beams follows a rhomboidlike pattern, and in which the walking beams are provided with dogs which project up over a fiat walking beam surface.

FIG. 9 is a side view showing diagrammatically the mutual positions between the stationary hearth and the movable beams of the embodiment illustrated in FIG. 7, in one stage of the cyclic movement of said beams. more specifically the return movement thereof,

FIG. 10 illustrates the mutual positions of the same elements subsequent to completion of the vertical, upwardly directed movement of the beams,

FIG. 11 illustrates the mutual positions of the same elements, subsequent to termination of the forward movement of the walking beams in one direction of movement obliquely upwards and forwards, during which all billets have been tipped over the respective crowns presented by their respective sloping conveying or support surfaces on the stationary hearth, and finally,

FIG. 12 illustrates the mutual positions of the same elements, subsequent to the lowering movement of the walking beams. FIGS. 1 and 2 illustrate diagrammatically a heating furnace or heat treatment furnace, the arch or furnace wall of which is generally indicated at 10. The stationary portion of the furnace hearth, which is indicated at 11, is passed through by, for example, two movable walking beams 12. Both the stationary portion 11 of the hearth and the walking beams 12 are provided with a number of sequentially arranged, obliquely forwardly and upwardly extending conveying or support surfaces 13 and 14, respectively, which merge into one another via abruptly declining surfaces 15 and 16, so as to form a dip in front of the crowns or lips 17 and 18 of respective conveying and support surfaces, which enable each billet 19 situated foremost on the conveying or support surfaces to be somersaulted or tipped at the end of each forward movement of walking beams 12. In the exemplary embodiment, the rolling billets, subsequent to falling, will be received by the conveying or support surfaces of the walking beams. which in certain instances may be a disadvantage in view of the mechanical sensitivity of the movably journaled beams to impact shocks, but which nevertheless does not detract from the practical significance of the embodiment in general. It should also be observed in this connection that the upper. extending surfaces of the crowns I7 and 18, as shown in FIG 1. are suitably arranged substantially parallel with the direction in which the moving beams move during the feeding stroke In the embodiment of FIG. 1, these surfaces are horizontal in conformity with the forward feeding movement As will be seen from FIG 1. the walking beams 12 are mounted on rollers 20 journaled in arms 22. which in turn are pivotable about horizontal shafts in a supporting frame structure or the like 23, so that the walking beams are lifted during upward swinging of the arms bearing the rollers 20. The arms 22 are operated by. for example. a pushand-pull rod 24.

which is capable of being actuated, for example, by means of the hydraulic or pneumatic drive means 25.

Depending from the bottom side of the walking beams 12 are bracket members 26, with which the piston rods of the pressure-medium-operated cylinders 27 are pivotally connected. The cylinders 27 are, in turn, pivotally mounted about horizontal shafts in the support structure 28. These prime movers, which are double acting, serve to impart to the walking beams the horizontal movement in both the raised and lowered position thereof. The working periods ofthe cylinders 25 and 27 are controlled cyclically in a known manner, by means of suitable control means.

In FIG. 1 the reference A indicates the infeed end of the furnace and B its outfeed end. The billets are fed to the furnace by means of pushing devices, generally indicated at 28, comprising normally hydraulic or pneumatic cylinders, while the billets are discharged from the furnace down a chute 29.

The function of the arrangement will be better understood from FIGS. 3-6, where like elements are identified with the same reference numerals as used with reference to FIGS. 1 and 2.

FIG. 3 shows a number of billets 19 resting on the inclined conveying or supporting surfaces 13 of the stationary hearth. The illustrated walking beam 12 has finished its rearward, horizontal movement, in the direction of arrow 30, i.e. the return movement. In FIG. 4, the walking beam has completed its return movement and executed a vertical lifting movement in the direction of arrow 31, so that a number of the elements are lifted and come to rest on the walking beam 12. As will be seen from FIG. 4, each leading billet remains, however, on the crown 17 of the conveying surface on the stationary hearth while the walking beam 12 moves to a position in which its abruptly declining surface 16 is located immediately behind said respective leading billets 19.

In this position, the walking beam 12 now starts its horizontal forward feed movement in a raised position, in the direction of arrow 32, as shown in FIG. 5. Consequently, the billets 19 remaining on the conveying surface of the hearth 11 are pushed by the declining surfaces of the walking beam, forwards and beyond the crown 17, whereby the billets while falling are turned through in a billet space created on the nearest preceding conveying surface 14 on the walking beam 12 by the feeding movement, and takes the position shown in FIG. 5, when the walking beam has completed its forward feed movement. The walking beam is lowered from this position, vertically in the direction of arrow 3, in accordance with the movement diagram illustrated in FIG. 6, so that all billets are unloaded from the conveying surface 13 of the stationary hearth l1, whereafter the above-described cyclic movement is repeated an unlimited number of times in the movement pattern graphically shown by the arrows in FIG. 6.

It is important that the distance moved through each step executed by the moving beams, and the spacing between the billets on the beams is so proportioned with regard to the distance between the abruptly declined surfaces that the latter distance is an even multiple of the length moved by the movable beam. In this way, the billets automatically adopt a position in front of the dip or abruptly declining surface, in which the abruptly vertically declining surface of the walking beam reaches behind the billet in the manner described above.

In order to avoid the aforementioned possibility of the billets hitting the movable beam when falling from the crown of the abruptly declining surface. the conveying surfaces of said beam at this moment being located over the surface of the stationary hearth, recesses can be made in the movable beam so that the surface thereof at the fall positions of the billets lies beneath the surface of the stationary hearth, and the billets thus fall onto the stationary hearth instead of the movable beam.

In the embodiment of the invention described in the aforegoing, relatively long, inclined conveying surfaces have been arranged, which are capable of supporting several billets at once. In this arrangement it is thus only possible to turn the billets once during their forward movement through the furnace.

If, on the'other hand, it is desired to turn all billets during the movement cycle of the moving beamsthe sloping conveying surfaces can instead be made short, so that the distance between the abruptly depending surfaces is equal to the feed length of the beams. wherewith only one billet at a time will rest on the conveying surfaces.

An embodiment of the arrangement modified in this respect is shown diagrammatically in FIG. 7, which illustrates substantially the same furnace system as that shown in FIGS. 1 and 2, although primarily with the difference that the stationary hearth, here indicated by the reference numeral 34, presents a large number of relatively short conveying surfaces 34 presenting a sawtooth appearance in said view and adapted to receive one billet 36 at a time.

The walking beam, indicated by the reference numeral 37 in this embodiment, presents a similar configuration having a large number of relatively short surfaces 38 of the same length as the surfaces 35- on the stationary hearth and the same degree of inclination.

Another difference with the embodiment of FIG. 7 in relation to that of FIGS. 1-6 is that the movable beams have been combined with devices which are adapted to impart to the beams a rhombic movement pattern, with the forward feed movement directed parallel with the conveying planes, i.e. obliquely forwards and For this purpose, the walking beams are provided on the undersurface thereof with a number of triangular shoulders on the like 39, which cooperate with support rollers 41 joumaled in pivot arms 40, in such a way that when said arms 40 are first swung upwards and the beams rest on the rollers and the abruptly depending surfaces 42 arrive behind their respective blanks 36, the walking beams, upon executing their forward feed movements are guided obliquely upwards and forwards by the surfaces of the shoulders 39 engaging the rollers 41. Upon completion of this latter movement, all billets are tipped or somersaulted over their respective abruptly depending surfaces and turned through 90 while simultaneously being moved forwards one step.

An embodiment of the somersaulting arrangements of the invention somewhat simplified in comparison with the arrangement of FIG. 7, is shown in FIG. 8, in which the stationary hearth, generally indicated at 43, coincides in construction with the hearth 44 of FIG. 7. The movable beams, indicated with the reference numerals 44, are provided, similar to the beams of the embodiment in FIG. 7, with the shoulders 39 and the support rollers 41 journaled in pivot arms. On the other hand, the beams of this embodiment are not provided with the oblique surfaces 38 as in the embodiment of FIG. 7, but instead present carrying membersor dogs 45 securely arranged to the beams and arranged in uniform spaced relationship therealong, suitably in the form of rods, which preferably have a slope of 90 to the carrier surfaces 46'on the stationary hearth. The movable beams are operated in the same way as in the embodiment of FIG. 7, which means that the dogs during the cyclic movement of the beams are lifted to positions behind their respective billets resting on the stationary hearth, and during the forward feed stroke, which takes place in an obliquely forward and' upward movement, project the billet over the corresponding crown on the stationary hearth, to turn the billet through 90 while simultaneously moving said billet forward one step.

To facilitate understanding of the sequence of happenings when somersaulting all the billets as they are fed through the furnace illustrated in FIG. 7, reference is made to the situations illustrated in FIGS. 9-12.

As with the embodiment of FIG. 7, the stationary hearth is identified by 34, the movable beams by 37 and the billets by 36.

In FIG. 9, which illustrates the billets 36 resting on the support surfaces 35 on the stationary hearth, the movable beams are found on their return movement, which, owin to the cooperation of shoulders 39 in FIG. 7 with the rollers 51, is effected in a direction obliquely backwards and downwards, as shown by the arrow 47.

Subsequent to the completion of this return movement, the beams are lifted vertically, as shown by the arrow 48 in FIG. 10, to the position illustrated in this figure.

Subsequent to completion of the lifting movement shown in FIG. 10, the beams are moved forward one step length in the direction of arrow 49, until the billets are tipped over the crowns on the stationary hearth, and fall down onto the surface 38 and take the position shown in FIG. 11.

FIG. 12 shows the beam subsequent to completing the lowering movement, during which the billets have been laid on the support surface 35 of the stationary hearth 34. A double arrow 51 indicates in FIG. 1 an alternative movement possibility for the movable beams. It is namely also possible to omit the vertical movements of the beams and permit them to make only one forward and backward movement, as shown by the arrow 51, in constant height position, as shown by arrow 49.

The arrangement shown in FIG. 8 with special dog or earrier members is to be considered a development of the last-mentioned alternative.

The invention is not restricted to the shown and described embodiments but can be varied within the scope of the following claims.

What I claim is:

1. An arrangement in heat treatment furnaces of the walking beam type for rotating billets of polygonal cross section during their passage therethrough comprising:

a. at least one billet-conveying beam mounted for movement in a parallelogrammatic cycle in relation to adjacent stationary portions of the furnace hearth;

b. support surfaces on the stationary hearth portion joined together by a downwardly inclined portion;

a plurality of upright billet-propelling surfaces on the movable beam extending sequentially in the longitudinal direction thereof, said surfaces being arranged to engage behind a billet resting on the stationary hearth portions and to propel the billet over the edge of the downwardly inclined portion thereof;

the junction between the forward movement of the movable beam and the point at which said beam is lowered out of contact with the billets being located so that the center of gravity of the billet to be rotated lies outside the edge of the downwardly extending portion of the stationary hearth portions when said beam is lowered.

2. The arrangement of claim 1 including a plurality of downwardly inclined portions in which the lips of said portions are in essentially the same plane.

3. The arrangement of claim 1 in which on the support surfaces, at least adjacent the lip of the downwardly inclined portion, are substantially parallel with the direction of movement of the walking beam during the forward feed movement.

4. The arrangement of claim 1 in which the extension of each support surface in the through feed direction of the furnace exceeds the length of the forward feed stroke of the walking beam.

5. The arrangement of claim 1 in which the extension of each support surface in the through feed direction of the furnace substantially coincides with the length of the forward feed stroke of the walking beam. 

1. An arrangement in heat treatment furnaces of the walking beam type for rotating billets of polygonal cross section during their passage therethrough comprising: a. at least one billet-conveying beam mounted for movement in a parallelogrammatic cycle in relation to adjacent stationary portions of the furnace hearth; b. support surfaces on the stationary hearth portion joined together by a downwardly inclined portion; c. a plurality of upright billet-propelling surfaces on the movable beam extending sequentially in the longitudinal direction thereof, said surfaces being arranged to engage behind a billet resting on the stationary hearth portions and to propel the billet over the edge of the downwardly inclined portion thereof; d. the junction between the forward movement of the movable beam and the point at which said beam is lowered out of contact with the billets being located so that the center of gravity of the billet to be rotated lies outside the edge of the downwardly extending portion of the stationary hearth portions when said beam is lowered.
 2. The arrangement of claim 1 including a plurality of downwardly inclined portions in which the lips of said portions are in essentially the same plane.
 3. The arrangement of claim 1 in which on the support surfaces, at least adjacent the lip of the downwardly inclined portion, are substantially parallel with the direction of movement of the walking beam during the forward feed movement.
 4. The arrangement of claim 1 in which the extension of each support surface in the through feed direction of the furnace exceeds the length of the forward feed stroke of the walking beam.
 5. The arrangement of claim 1 in which the extension of each support surface in the through feed direction of the furnace substantially coincides with the length of the forward feed stroke of the walking beam. 